1. Field of the Invention
The present invention relates to a method and a system for when measuring the dimension of a fine pattern shape of an LSI or the like, measuring the dimension of an object to be width-measured with accuracy.
2. Description of the Related Art
Heretofore, in accordance with the description in JP-A-6-347246 for example, in a critical dimension measurement scanning electron microscope (critical dimension measurement SEM) for applying an electron beam to a sample to measure the dimension of the sample, a cursor is adjusted to either a luminance leading part or a luminance trailing part of an object to be measured either on the secondary electron image or on the reflected electron image and the dimension between both sides of the cursor is, as a result, decided as the dimension of the object to be measured.
By the way, as for the technique for evaluating the diameter dimension of an electron beam, there are the techniques disclosed in JP-A-11-224640 and JP-A-11-25898, respectively.
In the technique disclosed in JP-A-6-347246, an electron beam is applied to an object to be measured while scanning the object with the electron beam being applied, and a sample image is formed depending on a quantity of secondary electrons and reflected electrons which have been emitted and generated therefrom, respectively, to measure the width of the object. There is, as a result, encountered the problem that an object to be measured is displayed in a larger size and a gap between patterns or the like is displayed in a smaller size as the diameter of the applied electron beam becomes larger.
While that problem is not so serious when the size of an object to be width-measured is much larger than the diameter of the applied electron beam, for an element which has the dimension only in the range of about several nano meters to about several tens nano meters as elements in recent semiconductor devices for example, the diameter of the applied electron beam (e.g., several nano meters) is so large as to be non-negligible against the size of such semiconductor devices. Thus, the difference occurs between the actual dimension value and the measured dimension value accordingly. There is, as a result, encountered the problem that the measurement accuracy is deteriorated.
In the light of the foregoing, the present invention has been made in order to solve the above-mentioned problems associated with the prior art, and it is, therefore, an object of the present invention to provide a method and a scanning electron microscope for measuring a width of an object on a sample which are capable of reducing or removing an error in width measurement resulting from the influence of the dimension of an electron beam diameter to obtain an accurate value of a measured width.
In order to attain the above-mentioned object, according to the present invention, there is provided a method of measuring a width of an object on a sample in which the sample is scanned with a beam to measure the width of an object to be width-measured on the sample on the basis of a secondary signal obtained from the sample, wherein the width-measured value of the object of the width measurement obtained on the basis of the secondary signal is corrected with a value with respect to a dimension value of the beam diameter.
By adopting such composition, the error in width measurement resulting from the influence of the beam diameter can be either reduced or eliminated. By the way, concrete examples of the present invention will be described in detail in DETAILED DESCRIPTION OF THE INVENTION.
Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings.